Lubricating oils containing organo-mo-
lybdenum tricarbonyl compounds



llnited States latent ice V r 3,175,971 LUBRICATING OILS CDNTAINiNGORGANO-MO- LYBDENUM TRICAREONYL COMPOUNDS Edwin L. De Young, Milwaukee,Wis, assignor to Standard Oil Company, Qhicago, 111., a corporation ofIndiana No Drawing. Filed Dec. 19, 1960, Ser. No. 76,473

3 Claims. (Cl. 252-33) This invention relates to novel oil-solubleorgano-molybdenum co-ordination compounds as new compositions of matter,and to 'compositions containing the same, which compositions possesscorrosion and/or oxidation inhibiting properties. More particularly, itconcerns novel oilsoluble hydrocarbyl substituted benzene molybdenumcarbonyl co-ordination compoundsand their use as additives to lubricantsto impart anti-oxidation characteristics thereto.

Within recent years it has become common practice to impart improvedproperties to lubricants through the use of various types of additivesor addition agents. Lubricating oils employed in internal combustionengines such as automotive and diesel engines requirethe use of one ormore addition agents to improve their serviceability under certainadverse operating'conditions. Among the more important additivesemployed are the type which function to prevent the formation andaccumulation of sludge and varnish-like'coatings on pistons and cylinderwalls of'the engine. Such additives which have the property ofmaintaining clean engines are referred to as detergent-type lubricantadditives. .The more effective addition agents which have been developedfor compounding with lubricantsaremany sulfur-containing organiccompounds such as, by way of example, sulfurized'terpenes, sulfurizedhydrocarbon oils, vegetable oils or animal oils, organic polysulfides,particularly polyalkyl polysuliides, metal salts of organo-substitutedthioacids of phosphorus, metal salts of the reaction product of aphosphorus sulfide and a hydrocarbon such as, for example, polybutenesand other polyolefins, and combinations of the foregoing.

Corrosion inhibitors also play an important part in the formulation ofefficient lubricants. Such corrosion inhibitors should effectivelyinhibit the corrosion of metal alloys of the type used in enginebearings and other engine parts. Recent increased use of silver andsimilar metals in the construction of improved internal combustionengines has created new problems in the use of. sulfur-containingadditives in lubricants for such engines; the primary problem createdbeing the corrosion of such silver parts of the engine by'thesulfur-containing. additives. While such corrosion can be eliminated byavoiding the use of sulfur-containing additives in lubricants for suchengines, this solution of the problem is accompanied by the lossof thehighly desired beneficial effects. of the additives of this type.

An object of the present invention is to provide novel oil-solubleorgano-molybdenum,co-ordination compounds anda method of preparing thesame. Another object is to provide novel oil-soluble organo-molybdenumcoordination compounds having particular utility as lubricantadditives.- A particular object is to provide novel oil-solublehydrocarbyl substituted benzene molybdenum carbonyl co-ordinationcompounds which have anti-oxidative properties in addition to havingsubstantial metal corrosion inhibiting properties when added to minerallubricating oils. A further object is to providea composition which willinhibit the corrosion of silver and similar metals by sulfur and/ororganic sulfur-containing compounds. Still another object is to providea method of inhibiting the corrosion of engine parts. in contact withlubricant compositions which contain sulfur and/ or organicsulfurcontaining compounds which are normally corrosive to specificexamples.

3,175,971 Patented Mar. 30, 1965 metals. Other objects and advantages ofthe present invention will become apparent from the ensuing descriptionthereof.

It has been discovered that certain novel oil-soluble hydrocarbylsubstituted benzene molybdenum carbonyl co-ordination compounds haveanti-oxidant and/ or anticorrosive properties. Such compounds areextremely useful as additives for lubricants which are normallycorrosive to metals with which such lubricants are in contact. Thus, inaccordance with the present invention, the oilsoluble molybdenumcarbonyl co-ordination compounds are prepared by reacting molybdenumhexacarbonyl with a hydrocarbyl substituted benzene having at least onealiphatic substituent containing at least four carbon atoms. Thereactants being employed in equimolar amounts, preferably with a slightexcess of the substituted benzene reactant. The reaction is carried outat atmospheric pressure and at temperatures of from about C. to about C.Depending upon the temperatures, employed, the reaction time may varyfrom about 18 hours to about 72 hours, or until evolution of carbonmonoxide ceases.

The new products are crystalline solids of varying oil solubilitydepending upon the amount and nature of hydrocarbon substitution in thestructure and nature of the base oil. They have particular value as,anti-oxidants for lubricating oil lubricants, as bearing corrosioninhibitors and, because they are non-corrosive to silver in lubricant,

compositions, have a wide range of applicability. In general, it isdesirable that the molybdenum carbonyl coordination compounds contain atleast-four carbon atoms, preferably 8 to 18 carbon atoms, in themonoaliphatic or polyaliphatic substituted benzene reactant in order toprovide adequate oil solubility. The products then can be handled in theform of mineral oil concentrates which facilitate handling in theformulation of commercial lubricating oils and greases. The level of usein the finished lubricant, however, is usually quite small. For use asan oxidation inhibitor in a hydrocarbon oil susceptible to oxidativedeterioration the concentration of the additive should be at least 0.2%by weight. Amounts above 0.5% give satisfactory results, but since suchresults may beobtained' with lesser amounts, it is usually noteconomical to employ more than 0.5%.

In commercial formulation, the substituted benzenemolybdenum-carbonylcompounds will ordinarily'be used,

as is customary in conjunction with other compatible lubricating oiladditives, for example, pour depressants, viscosity index improvers,anti-rust agents, anti-foam agents and the like. The base may compriseany hydrocarbon oil subject to oxidative deterioration. For mostapplications, the oil' will comprise a mineraLoil fraction of the usualviscous lubricating oil range.

The new oil-soluble organo-molybdenum co-ordination compounds of thepresent invention are the co-ordination reaction products of molybdenumhe'xacarbonyl' and an aliphatic substituted benzene, which co-ordinationreaction products have the general formula RMo (CO) wherein R is abenzene radical having at least one aliphatic substituent containing atleast four carbon atoms.

The aliphatic substituted benzene employed in preparing the molybdenumcarbonyl co-ordinationcompounds can be monoor poly, straight or branchedchain, aliphatie substituted benzenes. Examples of suitable benzenesare: butylbenzene, cyclopentylbenzene, hexylbenzene, octylbenzene,nonylbenzene, dodecylbenzene', hexadecylbenzene, octadecylbenzene,cyclohexylbenzene, and mixtures thereof.

The invention will be further illustrated by means of In the examples,dodecyl benzene is shown by way of example as representative of theclass of hydrocarbyl substituted benzenes which are suitable forpurposes of the present invention and the new additives were evaluatedby means of the modified stirring sand corrosion test (MSSCT) and themodified EMD silver bearing corrosion test.

The MSSCT test was run as follows: A copper-lead test specimen islightly abraided with steel wool, washed with naphtha, dried and weighedto the nearest milligram. The cleaned copper-lead test specimen issuspended in a glass beaker, cleaned with a hot tri-sodium phosphatesolution, rinsed with water, acetone and dried, and 300 grams of the oilto be tested, and 50 grams of a 3035 mesh sand charged to the beaker.The beaker is then placed in a bath or heating block and heated to atemperature of 330 F. (i2 F.) while the contents are stirred by means ofa stirrer rotating at 1300 r.p.m. The contents of the beaker aremaintained at this term perature for forty-eight hours, after which thecopperlead test specimen is removed, rinsed with naphtha, dried andweighed. The test specimen is then replaced in the beaker and the testcontinued for another twenty-four hours (seventy-two hours total). Atthe conclusion of this time, the test specimen is removed from thebeaker, rinsed with naphtha, dried and weighed.

In the modified EMD test a silver strip 2 cm. x 5.5 cm. with a smallhole at one end for suspension is lightly abraded with No. steel wool,wiped free of any adhering steel wool, washed with carbon tetrachloride,airdried and then weighed to 0.1 milligram. Three hundred cc. of the oilto be tested is placed in a 500 cc. lipless glass beaker and the oil isheated to a temperature of 300 F. (i2 F.) and the silver test stripsuspended in the oil so that the strip is completely immersed therein.The oil in the beaker is stirred by means of a glass stirrer operatingat 300 rpm. At the end of twenty-four hours, the silver strip is removedand while still hot rinsed thoroughly with carbon tetrachloride andair-dried. The appearance of the strip is then visually noted and givenratings according to the following scale:

1Bright 2Stained 3Grey-black 4Black, smooth 5--Black, flake and weighed.A weight loss of 20 mg. or less is considered passing.

Example I A charge of 88 grams (0.33 mole) of molybdenum hexacarbonyland 82 grams (.33 mole) of dodecyl benzene was placed in a glassreaction vessel equipped with a thermometer and stirrer. The mixture washeated at atmospheric pressure to 120 C. and held for approxi mately 24hours. Thereafter the reaction mixture was cooled and washed withacetone. After evaporation of the acetone the precipitate which formedin the reaction mixture was recovered by filtration and washed withhexane. 87 grams of light gray crystals were recovered having amolybdenum analysis of 20.5%. Calculated 22.5% molybdenum for dodecylbenzene molybdenum tricarbonyl. The crystals sublimed from 105 to 130 C.

The product was tested at the 0.5% concentration level in solventextracted SAE 40 grade Mid-Continent oil containing about 3% calciumpetroleum sulfonate and about 1.25% calcium sulfide phenate. The oilgave a gright EMD silver strip and MSSCT Weight losses of 103.5 mg. at48 hours and 294.6 mg. at 72 hours; whereas the same oil without theproduct of this example gave a MSSCT loss of 870.4 mg. at 48 hours.

Example II A solvent extracted SAE 30 grade Mid-Continent oil containingabout 3% of a detergent of the neutralized phosphorussulfide-polybutenes reaction product type gave 752.4 mg. weight loss at48 hours. When 0.5 of the product from Example I was added to the aboveoil the MSSCT losses Were 61.4 mg. at 48 hours and 134.4 mg. at 72hours.

Example III A solvent extracted SAE, 63 VI, grade Mid-Continent oil gaveMSSCT loss of 740.9 mg. at 48 hours. When 0.25% and 0.5 of the productfrom Example I was added to the above oil the MSSCT losses were 108.4mg. at 48 hours and 283.3 mg. at 72 hours, and 71.6 mg. at 48 hours and146.6 mg. at 72 hours, respectively.

Example IV The product was tested at 0.5% concentration level in solventextracted SAE 30 grade Mid-Continent oil containing about 3% of adetergent of the borated barium neutralized phosphorussulfide-polybutene reaction product type. The oil gave a bright EMDsilver strip and MSSCT weight losses of 96.1 mg. at 48 hours and 227.0mg. at 72 hours.

While the above-described reaction products can be suitably employedalone in combination with a base oil, they are usually used incombination with other lubricant addition agents which impart variousdesired characteristics to the base oil. Usually, these reactionproducts are used in conjunction with detergent-type additives,particularly those which contain sulfur or phosphorus and sulfuraddition agents. This type is usually used in amounts of from about0.002% to about 10%, and preferably from about 0.01% to about 5%. Amongthe phosphorusand sulfur-containing addition agents are the neutralizedreaction products with a phosphorus sulfide and a hydrocarbon, analcohol, a ketone, an amine or an ester. Of the phosphorus sulfidereaction product additives, I prefer to employ the neutralized reactionproducts of a phosphorus sulfide, such as a phosphorus pentasulfide, anda hydrocarbon of the type described in U.S. 2,316,082, issued to C. M.Loane et al., April 6, 1943. As taught in this patent, the preferredhydrocarbon constituent of the react-ion is a mono-olefin hydrocarbonpolymer resulting from the polymerization of low molecular weightmono-olefin hydrocarbons, such as propylene, butenes, amylenes orcopolymers thereof. Such polymers may be obtained by the polymerizationof mono-olefins of less than 6 carbon atoms in the presence of acatalyst, such as sulfuric acid, phosphoric acid, boron fluoride,aluminum chloride, or other similar halide catalysts of the Friedel-Crafts type.

The phosphorus sulfide-hydrocarbon reaction product normally shows atitratable acidity which is neutralized by treatment with a basicreagent. The phosphorus sulfidehydrocarbon reaction product, whenneutralized with a basic reagent containing a metal constituent, ischaracterized by the presence or retention of the metal constituent ofthe basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can beobtained by treating the acidic reaction product with a suitable basiccompound, such as hydroxide, carbonate, oxide or sulfide of an alkalineearth metal or an alkali metal, such as for example, potassiumhydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, bariumhydroxide, barium oxide, etc. Other basic reagents can be used, such asfor example, ammonia, or an alkyl or aryl-substituted ammonia, such asamines. The neutralization of the phosphorus sulfidehydrocarbon reactionproduct is carried out preferably in a non-oxidizing atmosphere bycontacting the acidic reaction product either as such or dissolved in asuitable solvent, such as naphtha with a solution of the basic reagent.As an alternative method, the reaction product can be treated Withsolidalkaline compounds, such as KOH, NaOH, Na CO CaO, BaO, Ba(OH) Na S, andthe like, at an elevated temperature of from about 100 F. to about 600F. Neutralized reaction products containing a heavy metal constituentsuch as for example, tin, tita nium, aluminum, chromium, cobalt, zinc,iron and the like can be obtained by reacting a salt of the desiredheavy metal with the phosphorus sulfide-hydrocarbon reaction productwhich has been treated with the phopshorus sulfide-hydrocarbon reactionproduct which has been treated with a basic reagent, such asabove-described.

Other phosphorus sulfide reaction products which can be used are thereaction products of a phosphorus sulfide and a fatty acid ester of thetype described in US. 2,399,243; the phosphorus sulfide-degras reactionproducts of US. 2,413,332; the reaction product of an alkylated phenolwith the condensation product of P 8 and turpentine of US. 2,409,877 andUS. 2,409,878; the reaction product of a phosphorus sulfide andstearonitrile of US. 2,416,807, etc.

The above-described molybdenum carbonyl compounds can be used incombination with lubricant base oils, such as hydrocarbon oils,synthetic hydrocarbon oils, such as those obtained by the polymerizationof hydrocarbons, such as olefin polymers, for example, polybutenes,polypropylene and mixtures thereof, etc; synthetic lubricating oils ofthe alkyleneoxide type, for example, the Ucon oils, marketed by Carbideand Carbon Corporation, as well as other synthetic oils, such as thepolycarboxylic acid ester-type-oils, such as the esters of adipic acid,se bacic acid, maleic acid, azelaic acid, etc.

While this invention has been described in connection with the use ofthe herein-described additives and lubricant compositions, their use isnot limited thereto; but the same can be used in products other thanlubricating oils, such as for example, fuel oils, insulating oils,greases, non-drying animal and vegetable oils, waxes. asphalts, and anyfuels for internal combustion engines, particularly where oxidation mustbe combatted.

Concentrates of a suitable oil base containing more than 10% of anoil-soluble hydrocanb-yl substituted benzene molybdenum carbonylcoordination compound alone or in combination with other additives canbe used for blending with hydrocarbon oils or other oils in theproportions desired for the particular conditions of use to give afinished product containing at least 0.2% of the molybdenum carbonylco-ordination compound.

Percentages given herein and in the appended claims are weightpercentages unless otherwise stated.

Although the present invention has been described with reference tospecific preferred embodiments thereof, the invention is not to beconsidered as limited thereto but includes within its scope suchmodifications and variations as come within the spirit of the appendedclaims.

I claim:

1. A mineral lubricating oil containing from about 0.2 to about 0.5% ofan oil-soluble organo-molybdenum tricarbonyl compound having the formulaRMo(CO) wherein R is benzene mono-substituted by alkyl of 4-18 carbonatoms.

2. A mineral lubricating oil containing from about 0.2 to about 0.5% ofdodecylbenzene molybdenum tricarbonyl.

3. A lubricating oil composition having improved oxidation stabilitycomprising (a) a major amount of a mineral lubricating oil base; (b)0.5% of dodecylbenzene molybdenum tricar'bonyl; (c) 3.0% of calciumpetroleum sulfonate; and (d) 1.25% of calcium sulfide phenate.

References Cited in the file of this patent UNITED STATES PATENTS2,818,417 Brown et al Dec. 31, 1957 2,849,399 Matuszak et a1. Aug. 28,1958 2,850,452 Sands et al. Sept. 2, 1958 2,952,523 Podall Sept. 13,1960 2,964,547 De Witt et a1. Dec. 13, 1960 2,993,922 Wyman July 25,1961 3,001,858 Antonsen Sept. 26, 1961 3,010,978 Antonsen Nov. 28 1961

3. A LUBRICATING OIL COMPOSITION HAVING IMPROVED OXIDATION STABILITYCOMPRISING (A) A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL BASE; (B)0.5% OF DODECYLBENZENE MOLYBDENUM TRICARBONYL; (C) 3.0% OF CALCIUMPETROLEUM SULFONATE; AND (D) 1.25% OF CALCIUM SULFIDE PHENATE.